1. Field of the Invention
The invention generally relates to ball and socket joints. The invention is specifically applicable tie rod ends in automotive steering and suspension systems.
2. Description of the Background Art
A typical prior art ball-and-socket joint comprises a case or housing in combination with a single ball integrated into one end of a main body, commonly known as spherical pin. This ball-and-socket joint assembly, correctly mounted, has a first fastening system on the external case, and a second fastening system at the opposite exposed end of the spherical pin assembly. Once the external case is attached to a movable part, and the spherical pin exposed end is attached to a separate part, the joint provides angular rotary movement between the respective parts. These types of joints are commonly used on vehicle steering and suspension systems. Depending on the specific application, the case and spherical pin may have different operational characteristics required to facilitate the specific function of the joint.
In operation, the ball-and-socket joint allows the swiveling movement of the spherical pin, but at the same time, restricts the angular movement of this spherical pin in certain directions, so that the force generated between the external case attachment point and the exposed end attachment point is communicated along the longitudinal axis of the spherical pin, as required in a functional tie rod or steering rod system.
In prior art systems, extreme angies between the spherical pin and the case, and rotational problems with the spherical pin have resulted in premature wear and failure. To address this problem, various solutions have been proposed, including alternative configurations of the case opening, and the replacement of the protective sealing cover of the ball-and-socket joint with a type of rubber bushing that, when compressed, imparts a spring effect to the assembly. However, neither of these techniques, either alone or in combination has resolved the wear problem. Additionally, the replacement protective cover incorporating the rubber bushing requires additional machining, increases production costs, and provides inferior protection relative to the original ball joint cover. If the ball joint cover fails, impurities such as dust, sand, and water can contaminate the joint and rapidly degrade its function until failure occurs. Further, the effective use of the prior art systems is limited to applications with little relative movement, and low stress on the spherical pin.
In order to eliminate these deficiencies, the present self-centering ball-and-socket joint has been developed. The present invention may be used in any system, but is designed primarily for those requiring angular movement restrictions of the spherical pin in certain directions, while retaining a free rotary movement capability. More specifically, the joint was designed for automotive tie rod applications. In operation, the invention functions to ensure that the tie rod will always be aligned with the other components of the system, and the self-centering function of the spherical pin operates to ensure that component forces are aligned with the spherical pin's longitudinal axis.